From: Narvaez, Pablo (Pablo.Narvaez@xxxxxxxxxxxxx)
Date: Sat Apr 06 2002 - 21:04:52 GMT-3
jeez, next-hop is available for both ... BUT what about sync? ....
-----Original Message-----
From: ying chang [mailto:ying_c@hotmail.com]
Sent: Sabado, 06 de Abril de 2002 05:47 p.m.
To: Narvaez, Pablo; Upp_and_Upp@hotmail.com; ccielab@groupstudy.com
Subject: RE: BGP MED - again
Here we go:
r3#sh ip bgp 192.168.1.0
BGP routing table entry for 192.168.1.0/24, version 7
Paths: (2 available, best #2, table Default-IP-Routing-Table)
Advertised to non peer-group peers:
26.1.1.2 36.1.1.6
1 1 1, (received & used)
26.1.1.2 (metric 20) from 26.1.1.2 (26.1.1.2)
Origin IGP, metric 20, localpref 100, valid, internal, not
synchronized
1, (received & used)
10.1.1.1 from 10.1.1.1 (192.168.1.1)
Origin IGP, metric 30, localpref 100, valid, external, best
r3#ping 26.1.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 26.1.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/8 ms
r3#ping 10.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/34/36 ms
r3#
Thanks,
Chang
>From: "Narvaez, Pablo" <Pablo.Narvaez@getronics.com>
>Reply-To: "Narvaez, Pablo" <Pablo.Narvaez@getronics.com>
>To: "ying chang" <ying_c@hotmail.com>, <Upp_and_Upp@hotmail.com>,
><ccielab@groupstudy.com>
>Subject: RE: BGP MED - again
>Date: Sat, 6 Apr 2002 17:27:47 -0600
>
>ummm I think your route is damnt hehe .... sorry about that. ummmm if you
>check the attribs between them you'll see that
>r3 is choosing "theorically" the worst route. Weight is the same,
>Local-Pref is better thru 26.1.1.2, asp-path is shorter thru 26.1.1.2 and
>also med is lower .... can you do a "show ip bgp 192.168.1.0" ... at the
>first sight I wonder why that route is going thru 10.1.1.1 instead of
>26.1.1.2.
>
>
>The only thing that comes to my head is the next hop is not available or if
>that route is internal, you have sync enabled and that route is not known
>thru IGP.
>
>hockito :o
>
>-----Original Message-----
>From: ying chang [mailto:ying_c@hotmail.com]
>Sent: Sabado, 06 de Abril de 2002 05:17 p.m.
>To: Narvaez, Pablo; Upp_and_Upp@hotmail.com; ccielab@groupstudy.com
>Subject: RE: BGP MED - again
>
>
>Hi hockito,
>
>Sorry, you are right. Can you explain why I get the following (192.168.1.0)
>which is the route from R1:
>
>r3#sib
>BGP table version is 5, local router ID is 36.1.1.3
>Status codes: s suppressed, d damped, h history, * valid, > best, i -
>internal
>Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
>*>i26.1.1.0/24 36.1.1.6 0 100 0 i
>*> 36.1.1.0/24 0.0.0.0 0 32768 i
>* i 36.1.1.6 0 100 0 i
>* i192.168.1.0 26.1.1.2 20 100 0 1 i
>*> 10.1.1.1 30 0 1 1 1 i
>r3#
>
>Thanks,
>Chang
>
>
> >From: "Narvaez, Pablo" <Pablo.Narvaez@getronics.com>
> >Reply-To: "Narvaez, Pablo" <Pablo.Narvaez@getronics.com>
> >To: "ying chang" <ying_c@hotmail.com>, <Upp_and_Upp@hotmail.com>,
> ><ccielab@groupstudy.com>
> >Subject: RE: BGP MED - again
> >Date: Sat, 6 Apr 2002 16:55:11 -0600
> >
> >ummm isn't as-path compared first that ibgp vs ebgp ?
> >
> >I'll ommit some attribs checked in between for path selection, but isn't
> >like this: (?)
> >
> >- weight
> >- local-pref
> >- as-path
> >- med
> >- ebgp vs ibgp
> >
> >??
> >
> >So that would give us as-path comparision before ebgp-igrp, correct?
> >
> >If you prepend from r2 to r3 thru r6, I think r3 will send that route
> >prepended, which cause that r1 selects that route thru r2. This way
>you'll
> >have touched only r2 and r1 will see r1-r2.
> >
> >Am I right?
> >
> >hockito
> >
> >
> >
> >
> >-----Original Message-----
> >From: ying chang [mailto:ying_c@hotmail.com]
> >Sent: Sabado, 06 de Abril de 2002 04:29 p.m.
> >To: Upp_and_Upp@hotmail.com; ccielab@groupstudy.com
> >Subject: Re: BGP MED - again
> >
> >
> >Hi Sean,
> >
> >Thanks. Please check R3's BGP table. My topology is
> >
> > -----R1(AS1)-----
> > | |
> > R2 R3
> > |----R6---------| (R2, R3, R6 are in AS236)
> >
> >As you can see MED is comparision is skipped. as-path will not do
>anything
> >for this case, because ebgp route is preferred as we've seen from Peter's
> >example - as-path comparision come after ebgp-ibgp comparision.
> >
> >Thanks,
> >Chang
> >
> >R1: AS1 (ISP router)
> >
> >interface Loopback0
> >ip address 192.168.1.1 255.255.255.0
> >!
> >interface Ethernet0
> >no ip address
> >shutdown
> >!
> >interface Serial0
> >ip address 10.1.1.1 255.255.255.0
> >encapsulation frame-relay
> >no fair-queue
> >frame-relay map ip 10.1.1.2 110 broadcast
> >frame-relay map ip 10.1.1.3 120 broadcast
> >no frame-relay inverse-arp
> >!
> >router bgp 1
> >bgp log-neighbor-changes
> >network 192.168.1.0
> >neighbor 10.1.1.2 remote-as 236
> >neighbor 10.1.1.2 soft-reconfiguration inbound
> >neighbor 10.1.1.2 route-map set-med1 out
> >neighbor 10.1.1.3 remote-as 236
> >neighbor 10.1.1.3 soft-reconfiguration inbound
> >neighbor 10.1.1.3 route-map set-med2 out
> >!
> >!
> >route-map set-med2 permit 10
> >set metric 30
> >set as-path prepend 1 1
> >!
> >route-map set-med1 permit 10
> >set metric 20
> >!
> >
> >R2: (AS236, border router 1 to R1)
> >!
> >interface Ethernet1
> >ip address 26.1.1.2 255.255.255.0
> >!
> >interface Serial0
> >ip address 10.1.1.2 255.255.255.0
> >encapsulation frame-relay
> >no fair-queue
> >frame-relay map ip 10.1.1.1 111 broadcast
> >frame-relay map ip 10.1.1.3 111 broadcast
> >!
> >router ospf 100
> >router-id 26.1.1.2
> >log-adjacency-changes
> >passive-interface default
> >no passive-interface Ethernet1
> >no passive-interface Serial0
> >network 0.0.0.0 255.255.255.255 area 0
> >!
> >router bgp 236
> >bgp router-id 26.1.1.2
> >bgp always-compare-med
> >bgp log-neighbor-changes
> >neighbor 10.1.1.1 remote-as 1
> >neighbor 10.1.1.1 soft-reconfiguration inbound
> >neighbor 26.1.1.6 remote-as 236
> >neighbor 26.1.1.6 next-hop-self
> >neighbor 36.1.1.3 remote-as 236
> >neighbor 36.1.1.3 next-hop-self
> >neighbor 36.1.1.3 soft-reconfiguration inbound
> >!
> >
> >R3: (AS236, border router 2 to R1)
> >
> >!
> >interface Ethernet0
> >ip address 36.1.1.3 255.255.255.0
> >!
> >interface Serial0
> >ip address 10.1.1.3 255.255.255.0
> >encapsulation frame-relay
> >no fair-queue
> >frame-relay map ip 10.1.1.1 121 broadcast
> >frame-relay map ip 10.1.1.2 121 broadcast
> >!
> >!
> >router ospf 100
> >router-id 36.1.1.3
> >log-adjacency-changes
> >passive-interface default
> >no passive-interface Ethernet0
> >no passive-interface Serial0
> >network 0.0.0.0 255.255.255.255 area 0
> >!
> >router bgp 236
> >bgp always-compare-med
> >bgp log-neighbor-changes
> >bgp always-compare-med
> >network 36.1.1.0 mask 255.255.255.0
> >neighbor 10.1.1.1 remote-as 1
> >neighbor 10.1.1.1 soft-reconfiguration inbound
> >neighbor 26.1.1.2 remote-as 236
> >neighbor 26.1.1.2 next-hop-self
> >neighbor 26.1.1.2 soft-reconfiguration inbound
> >neighbor 36.1.1.6 remote-as 236
> >neighbor 36.1.1.6 next-hop-self
> >neighbor 36.1.1.6 soft-reconfiguration inbound
> >!
> >
> >(R6: internal router, IBGP to R2 and R3 only)
> >!
> >interface Ethernet0
> >ip address 26.1.1.6 255.255.255.0
> >!
> >interface Ethernet1
> >ip address 36.1.1.6 255.255.255.0
> >!
> >!
> >router ospf 100
> >router-id 36.1.1.6
> >log-adjacency-changes
> >passive-interface default
> >no passive-interface Ethernet0
> >no passive-interface Ethernet1
> >network 0.0.0.0 255.255.255.255 area 0
> >!
> >router bgp 236
> >no synchronization
> >bgp router-id 36.1.1.6
> >bgp always-compare-med
> >bgp log-neighbor-changes
> >bgp deterministic-med
> >network 26.1.1.0 mask 255.255.255.0
> >network 36.1.1.0 mask 255.255.255.0
> >neighbor 26.1.1.2 remote-as 236
> >neighbor 26.1.1.2 soft-reconfiguration inbound
> >neighbor 36.1.1.3 remote-as 236
> >neighbor 36.1.1.3 soft-reconfiguration inbound
> >!
> >-------------------------------------------------------
> >BGP tables
> >-------------------------------------------------------
> >r1#sib
> >BGP table version is 25, local router ID is 192.168.1.1
> >Status codes: s suppressed, d damped, h history, * valid, > best, i -
> >internal
> >Origin codes: i - IGP, e - EGP, ? - incomplete
> >
> > Network Next Hop Metric LocPrf Weight Path
> >* 26.1.1.0/24 10.1.1.2 0 236 i
> >*> 10.1.1.3 0 236 i
> >* 36.1.1.0/24 10.1.1.2 0 236 i
> >*> 10.1.1.3 0 0 236 i
> >*> 192.168.1.0 0.0.0.0 0 32768 i
> >r1#
> >termserv#2
> >[Resuming connection 2 to r2 ... ]
> >
> >r2#sib
> >BGP table version is 4, local router ID is 26.1.1.2
> >Status codes: s suppressed, d damped, h history, * valid, > best, i -
> >internal
> >Origin codes: i - IGP, e - EGP, ? - incomplete
> >
> > Network Next Hop Metric LocPrf Weight Path
> >*>i26.1.1.0/24 26.1.1.6 0 100 0 i
> >*>i36.1.1.0/24 26.1.1.6 0 100 0 i
> >* i 36.1.1.3 0 100 0 i
> >*> 192.168.1.0 10.1.1.1 20 0 1 i
> >* i 36.1.1.3 30 100 0 1 1 1 i
> >r2#
> >termserv#3
> >[Resuming connection 3 to r3 ... ]
> >
> >r3#sib
> >BGP table version is 5, local router ID is 36.1.1.3
> >Status codes: s suppressed, d damped, h history, * valid, > best, i -
> >internal
> >Origin codes: i - IGP, e - EGP, ? - incomplete
> >
> > Network Next Hop Metric LocPrf Weight Path
> >*>i26.1.1.0/24 36.1.1.6 0 100 0 i
> >*> 36.1.1.0/24 0.0.0.0 0 32768 i
> >* i 36.1.1.6 0 100 0 i
> >* i192.168.1.0 26.1.1.2 20 100 0 1 i
> >*> 10.1.1.1 30 0 1 1 1 i
> >r3#
> >termserv#6
> >[Resuming connection 6 to r6 ... ]
> >
> >r6#sib
> >BGP table version is 8, local router ID is 36.1.1.6
> >Status codes: s suppressed, d damped, h history, * valid, > best, i -
> >internal
> >Origin codes: i - IGP, e - EGP, ? - incomplete
> >
> > Network Next Hop Metric LocPrf Weight Path
> >*> 26.1.1.0/24 0.0.0.0 0 32768 i
> >*> 36.1.1.0/24 0.0.0.0 0 32768 i
> >* i 36.1.1.3 0 100 0 i
> >*>i192.168.1.0 26.1.1.2 20 100 0 1 i
> >* i 36.1.1.3 30 100 0 1 1 1 i
> >r6#
> >
> >
> >
> > >From: "Sean C." <Upp_and_Upp@hotmail.com>
> > >Reply-To: "Sean C." <Upp_and_Upp@hotmail.com>
> > >To: "ying chang" <ying_c@hotmail.com>, <ccielab@groupstudy.com>
> > >Subject: Re: BGP MED - again
> > >Date: Sat, 6 Apr 2002 16:50:54 -0800
> > >
> > >Hi Chang,
> > >
> > >Concerning your question of how to manipulate routes so the routes will
> >be
> > >preferred on the R1-R3 link over R2-R3 routes while not being able to
> > >change
> > >the configs on R1 and R3 (in other words - you can only work on R3) -
>add
> >a
> > >route-map on R3 and prepend R3's own AS# to routes being advertised to
> >R2.
> > >Since shorter AS paths are preferred, the routes will all come in on
>the
> > >R1-R3 route which has a shorter AS path. Plus, you don't have to
> > >manipulate anything on R2 and R1.
> > >
> > >Hope this helps,
> > >Sean
> > >----- Original Message -----
> > >From: "ying chang" <ying_c@hotmail.com>
> > >To: <dan_schaw@yahoo.com>; <jgraun@attbi.com>; <pdostal@724.com>;
> > ><ccielab@groupstudy.com>
> > >Sent: Saturday, April 06, 2002 12:47 PM
> > >Subject: RE: BGP MED - again
> > >
> > >
> > >Well, "bgp always compared Med" would not work help in this case as
>they
> > >both come from AS1.
> > >
> > >There are two web pages are helpful:
> > >
> > >http://www.cisco.com/warp/public/459/bgp-med.html
> > >http://www.cisco.com/warp/public/459/37.html
> > >
> > >Here's my question, if we stick on the original problem, which is we
>are
> > >trying to tell AS1 to prefer R1-R3 route instead of R2-R3 route, how
>can
> >we
> > >do it without changing anything on either R1 or R2? Can it be done? In
> > >simple term, R1 and R2 are proctor's routers, and you have to work on
>R3
> >to
> > >make R1 and R2 always prefer R1-R3 route.
> > >
> > >Thanks,
> > >Chang
> > >
> > >
> > > >From: Muhamamd Durrani <dan_schaw@yahoo.com>
> > > >Reply-To: Muhamamd Durrani <dan_schaw@yahoo.com>
> > > >To: Jason <jgraun@attbi.com>, "'Peter Dostal'" <pdostal@724.com>,
> > > >ccielab@groupstudy.com
> > > >Subject: RE: BGP MED
> > > >Date: Fri, 5 Apr 2002 23:00:57 -0800 (PST)
> > > >
> > > >you should use "bgp always compared Med " command to
> > > >force BGP to compare MED for destination from
> > > >Different AS systems . By default BGP donot compare
> > > >MED for same destinations from neighbors from
> > > >different AS.
> > > >
> > > >So R2 must have this command and than verify ur result
> > > >....
> > > >
> > > >Regards,
> > > >Muhammad
> > > >
> > > >
> > > >--- Jason <jgraun@attbi.com> wrote:
> > > > > Well iBGP as an Admin distance of 200 while eBGP has
> > > > > an admin distance
> > > > > of 20
> > > > >
> > > > > -----Original Message-----
> > > > > From: nobody@groupstudy.com
> > > > > [mailto:nobody@groupstudy.com] On Behalf Of
> > > > > Peter Dostal
> > > > > Sent: Friday, April 05, 2002 6:58 PM
> > > > > To: ccielab@groupstudy.com
> > > > > Subject: BGP MED
> > > > >
> > > > > I have a problem with BGP path selection process.
> > > > > Based on the BGP path
> > > > > selection process I would say that router R2 should
> > > > > choose iBGP path
> > > > > over
> > > > > eBGP (because of lower MED). Any suggestions?
> > > > > Thanks,
> > > > >
> > > > > Peter
> > > > >
> > > > >
> > > > > R1----FrameRelay----R2
> > > > > | |
> > > > > ------Ethernet-------
> > > > > |
> > > > > R3
> > > > >
> > > > > *********************************************
> > > > > hostname R1
> > > > > !
> > > > > interface FastEthernet1/1
> > > > > ip address 192.168.2.3 255.255.255.0
> > > > > !
> > > > > interface Serial1/0
> > > > > ip address 192.168.1.1 255.255.255.0
> > > > > encapsulation frame-relay
> > > > > no keepalive
> > > > > no fair-queue
> > > > > frame-relay interface-dlci 100
> > > > > !
> > > > > router bgp 2
> > > > > bgp log-neighbor-changes
> > > > > neighbor 192.168.1.2 remote-as 2
> > > > > neighbor 192.168.1.2 next-hop-self
> > > > > neighbor 192.168.2.1 remote-as 1
> > > > > neighbor 192.168.2.1 route-map BGP_MAP in
> > > > > no auto-summary
> > > > > !
> > > > > route-map BGP_MAP permit 10
> > > > > set local-preference 100
> > > > >
> > > > > *********************************************
> > > > > hostname R2
> > > > > !
> > > > > interface FastEthernet0/0
> > > > > ip address 192.168.2.2 255.255.255.0
> > > > > !
> > > > > interface Serial0/0
> > > > > ip address 192.168.1.2 255.255.255.252
> > > > > encapsulation frame-relay
> > > > > no keepalive
> > > > > no fair-queue
> > > > > frame-relay interface-dlci 100
> > > > > !
> > > > > router bgp 2
> > > > > bgp log-neighbor-changes
> > > > > neighbor 192.168.1.1 remote-as 2
> > > > > neighbor 192.168.1.1 next-hop-self
> > > > > neighbor 192.168.2.1 remote-as 1
> > > > > neighbor 192.168.2.1 route-map BGP_MAP in
> > > > > no auto-summary
> > > > > !
> > > > > route-map BGP_MAP permit 10
> > > > > set local-preference 100
> > > > > !
> > > > > *********************************************
> > > > > hostname R3
> > > > > !
> > > > > interface FastEthernet0/1
> > > > > ip address 192.168.2.1 255.255.255.0
> > > > > !
> > > > > interface Loopback0
> > > > > ip address 170.2.1.1 255.255.255.240
> > > > > !
> > > > > router bgp 1
> > > > > bgp log-neighbor-changes
> > > > > network 170.2.1.0 mask 255.255.255.240
> > > > > neighbor 192.168.2.2 remote-as 2
> > > > > neighbor 192.168.2.2 route-map BGP_MAP out
> > > > > neighbor 192.168.2.3 remote-as 2
> > > > > no auto-summary
> > > > > !
> > > > > route-map BGP_MAP permit 10
> > > > > set metric 20
> > > > >
> > > > > *********************************************
> > > > > R1#sh ip bgp
> > > > > BGP table version is 8, local router ID is
> > > > > 172.10.1.1
> > > > > Status codes: s suppressed, d damped, h history, *
> > > > > valid, > best, i -
> > > > > internal
> > > > > Origin codes: i - IGP, e - EGP, ? - incomplete
> > > > >
> > > > > Network Next Hop Metric
> > > > > LocPrf Weight Path
> > > > > *> 170.2.1.0/28 192.168.2.1 0
> > > > > 100 0 1 i
> > > > > * i 192.168.1.2 20
> > > > > 100 0 1 i
> > > > > *********************************************
> > > > > R2#sh ip bgp
> > > > > BGP table version is 8, local router ID is
> > > > > 192.168.2.2
> > > > > Status codes: s suppressed, d damped, h history, *
> > > > > valid, > best, i -
> > > > > internal
> > > > > Origin codes: i - IGP, e - EGP, ? - incomplete
> > > > >
> > > > > Network Next Hop Metric
> > > > > LocPrf Weight Path
> > > > > * i170.2.1.0/28 192.168.1.1 0
> > > > > 100 0 1 i
> > > > > *> 192.168.2.1 20
> > > > > 100 0 1 i
> > > > > *********************************************
> > > > >
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:57:58 GMT-3